From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
Joerg Roedel <joro@8bytes.org>,
David Woodhouse <dwmw2@infradead.org>,
Alex Williamson <alex.williamson@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>
Cc: baolu.lu@linux.intel.com, "Raj, Ashok" <ashok.raj@intel.com>,
"Bie, Tiwei" <tiwei.bie@intel.com>,
"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Sun, Yi Y" <yi.y.sun@intel.com>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [RFC PATCH v2 08/10] vfio/type1: Add domain at(de)taching group helpers
Date: Wed, 26 Sep 2018 10:11:03 +0800 [thread overview]
Message-ID: <1b4c12c3-1dc2-d9ba-9ba4-5220db3e2302@linux.intel.com> (raw)
In-Reply-To: <75517c87-6ffd-2023-a541-3c69ae52ef4b@arm.com>
Hi,
On 09/26/2018 01:55 AM, Jean-Philippe Brucker wrote:
> On 19/09/2018 00:26, Tian, Kevin wrote:
>>> If the core actually calls it, we can implement detach_dev :) The
>>> problem is that the core never calls detach_dev when default_domain is
>>> present (affects any IOMMU driver that relies on default_domain,
>>> including AMD), and even in case 4) the default_domain is present for
>>> the parent device
>>
>> Then can we change that core logic so detach_dev is invoked in all
>> cases? yes there will be some changes in vendor drivers, but I expect
>> this change trivial (especially considering the gain in IOMMU API
>> simplicity side as described below).
>
> Thinking more about this, there might be a way that doesn't require too
> much rewriting of IOMMU drivers. When VFIO calls iommu_detach_group to
> detach a vfio-pci device from its domain, it could do detach_dev(dev,
> old_domain) followed by attach_dev(dev, default_domain) instead of only
> attach_dev(dev, default_domain), so:
>
> __iommu_attach_group(grp, unmanaged_domain)
> ops->attach_dev(dev, unmanaged_domain)
> -> IOMMU driver detaches from default_domain only if the dev isn't
> in auxiliary mode
>
> __iommu_detach_group(grp, unmanaged_domain)
> if (ops->detach_dev)
> ops->detach_dev(dev, unmanaged_domain)
> ops->attach_dev(dev, default_domain)
> -> IOMMU driver ignores this if still attached to default_domain
>
This looks good to me.
Just a minor change to make it more readable.
__iommu_detach_group(grp, unmanaged_domain)
if (ops->detach_dev)
ops->detach_dev(dev, unmanaged_domain)
if (default_domain)
ops->attach_dev(dev, default_domain)
Best regards,
Lu Baolu
> It's not trivial: since half the IOMMU drivers seem to be using default
> domain now, their detach_dev callback might have been dead code for a
> while (I can't find a path where it still gets called), so re-enabling
> it requires some attention. However, since most of them won't care about
> aux domains, maybe we could just remove their detach_dev pointer.
>
> The resulting logic of attach/detach_dev in IOMMU drivers that do use
> aux domains still seems unnecessarily convoluted. It could as well be
> done with separate attach_aux/detach_aux functions. If you want to keep
> it that way though, I think the above could work for us and I'll try to
> write an RFC.
>
> Thanks,
> Jean
>
next prev parent reply other threads:[~2018-09-26 2:14 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 4:09 [RFC PATCH v2 00/10] vfio/mdev: IOMMU aware mediated device Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 01/10] iommu: Add APIs for multiple domains per device Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 02/10] iommu/vt-d: Add multiple domains per device query Lu Baolu
2018-09-05 19:35 ` Alex Williamson
2018-09-06 0:54 ` Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 03/10] iommu/amd: Add default branch in amd_iommu_capable() Lu Baolu
2018-09-05 19:37 ` Alex Williamson
2018-09-06 0:55 ` Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 04/10] iommu/vt-d: Enable/disable multiple domains per device Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 05/10] iommu/vt-d: Attach/detach domains in auxiliary mode Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 06/10] iommu/vt-d: Return ID associated with an auxiliary domain Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 07/10] vfio/mdev: Add mediated device domain type Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 08/10] vfio/type1: Add domain at(de)taching group helpers Lu Baolu
2018-09-10 16:23 ` Jean-Philippe Brucker
2018-09-12 5:02 ` Lu Baolu
2018-09-12 17:54 ` Jean-Philippe Brucker
2018-09-13 0:35 ` Tian, Kevin
2018-09-14 14:45 ` Jean-Philippe Brucker
2018-09-15 2:36 ` Tian, Kevin
2018-09-18 15:52 ` Jean-Philippe Brucker
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19130EAD7@SHSMSX101.ccr.corp.intel.com>
2018-09-19 2:10 ` Lu Baolu
2018-09-25 17:55 ` Jean-Philippe Brucker
2018-09-26 2:11 ` Lu Baolu [this message]
2018-08-30 4:09 ` [RFC PATCH v2 09/10] vfio/type1: Determine domain type of an mdev group Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 10/10] vfio/type1: Attach domain for " Lu Baolu
2018-09-05 3:01 ` [RFC PATCH v2 00/10] vfio/mdev: IOMMU aware mediated device Tian, Kevin
2018-09-05 19:15 ` Alex Williamson
2018-09-06 1:29 ` Lu Baolu
2018-09-10 16:22 ` Jean-Philippe Brucker
2018-09-12 2:42 ` Lu Baolu
2018-09-12 17:54 ` Jean-Philippe Brucker
2018-09-13 0:19 ` Tian, Kevin
2018-09-13 15:03 ` Jean-Philippe Brucker
2018-09-13 16:55 ` Raj, Ashok
2018-09-14 14:39 ` Jean-Philippe Brucker
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D191302ECE@SHSMSX101.ccr.corp.intel.com>
2018-09-14 14:40 ` Jean-Philippe Brucker
2018-09-14 21:04 ` Jacob Pan
2018-09-18 15:46 ` Jean-Philippe Brucker
2018-09-19 2:22 ` Tian, Kevin
2018-09-20 15:53 ` Jacob Pan
2018-09-14 2:46 ` Lu Baolu
2018-09-14 2:53 ` Tian, Kevin
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